Use for/empty instead of if/else/if checks to leave error message for empty array.
Use for/empty instead of if/else/if checks to leave error message for empty array.

CenterForOpenScience/lookit-api,pattisdr/lookit-api,CenterForOpenScience/lookit-api,CenterForOpenScience/lookit-api,pattisdr/lookit-api,pattisdr/lookit-api